Protective effect of panaxatriol saponins extracted from Panax notoginseng against MPTP-induced neurotoxicity in vivo

Elevating the significance of legume intake: A novel strategy to counter aging-related mitochondrial dysfunction and physical decline

Mitochondrial dysfunction increasingly becomes a target for promoting healthy aging and longevity. The dysfunction of mitochondria with age ultimately leads to a decline in physical functions. Among them, biogenesis dysfunction and the imbalances in the metabolism of reactive oxygen species and mitochondria as signaling organelles in the aging process have aroused our attention. Dietary intervention in mitochondrial dysfunction and physical decline during aging processes is essential, and greater attention should be directed toward healthful legume intake. Legumes are constantly under investigation for their nutritional and bioactive properties, and their consumption may yield antiaging and mitochondria-protecting benefits. This review summarizes mitochondrial dysfunction with age, discusses the benefits of legumes on mitochondrial function, and introduces the potential role of legumes in managing aging-related physical decline. Additionally, it reveals the benefits of legume intake for the elderly and offers a viable approach to developing legume-based functional food.

Regulation of mitophagy and mitochondrial function: Natural compounds as potential therapeutic strategies for Parkinson's disease

Mitochondrial damage is associated with the development of Parkinson's disease (PD), indicating that mitochondrial-targeted treatments could hold promise as disease-modifying approaches for PD. Notably, natural compounds have demonstrated the ability to modulate mitochondrial-related processes. In this review article, we discussed the possible neuroprotective mechanisms of natural compounds against PD in modulating mitophagy and mitochondrial function. A comprehensive literature search on natural compounds related to the treatment of PD by regulating mitophagy and mitochondrial function was conducted from PubMed, Web of Science and Chinese National Knowledge Infrastructure databases from their inception until April 2023. We summarize recent advancements in mitophagy's molecular mechanisms, including upstream and downstream processes, and its relationship with PD-related genes or proteins. Importantly, we highlight how natural compounds can therapeutically regulate various mitochondrial processes through multiple targets and pathways to alleviate oxidative stress, neuroinflammation, Lewy's body aggregation and apoptosis, which are key contributors to PD pathogenesis. Unlike the single-target strategy of modern medicine, natural compounds provide neuroprotection against PD by modulating various mitochondrial-related processes, including ameliorating mitophagy by targeting the PINK1/parkin pathway, the NIX/BNIP3 pathway, and autophagosome formation (i.e., LC3 and p62). Given the prevalence of mitochondrial damage in various neurodegenerative diseases, exploring the exact mechanism of natural compounds on mitophagy and mitochondrial dysfunction could shed light on the development of highly effective disease-modifying or adjuvant therapies targeting PD and other neurodegenerative disorders.

Neuroprotective effect of a medium-chain triglyceride ketogenic diet on MPTP-induced Parkinson's disease mice: a combination of transcriptomics and metabolomics in the substantia nigra and fecal microbiome

The ketogenic diet (KD) is a low carbohydrate and high-fat protein diet. It plays a protective role in neurodegenerative diseases by elevating the levels of ketone bodies in blood, regulating central and peripheral metabolism and mitochondrial functions, inhibiting neuroinflammation and oxidative stress, and altering the gut microbiota. However, studies on ketogenic therapy for Parkinson's disease (PD) are still in their infancy. Therefore, we examined the possible protective effect of KD in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model, examined the mouse gut microbiota and its metabolites, and performed transcriptomics and metabolomics on the substantia nigra of mice. Our results showed that a long-term medium-chain triglyceride KD (MCT-KD) significantly reduced MPTP-induced damage to dopaminergic (DA) neurons, exerted antioxidant stress through the PI3K/Akt/Nrf2 pathway, and reversed oxidative stress in DA neurons. The MCT-KD also reduced mitochondrial loss, promoted ATP production, and inhibited the activation of microglia to protect DA neurons in MPTP-induced PD mice. MCT-KD altered the gut microbiota and consequently changed the metabolism of substantia nigra neurons through gut microbiota metabolites. Compared to the MPTP group, MCT-KD increased the abundance of gut microbiota, including Blautia and Romboutsia. MCT-KD also affects purine metabolism in the substantia nigra pars compacta (SNpc) by altering fecal metabolites. This study shows that MCT-KD has multiple protective effects against PD.

Swimming training and herbal nanoformulations as natural remedies to improve sensory-motor impairment in rat midbrain tumor models: system biology, behavioral test, and experimental validation

Motor impairment worsens health-related quality of life in patients with primary and metastatic midbrain tumors. Here, 56-male-Wistar rats were divided into eight groups: Normal group, Midbrain Tomur Model group, Model + Exe group, Model + Lipo, Model + Extract, Model + Lipo-Extract, Model + Extract-Exe, Model + Lipo-Extract + Exe. According to the aim, mid-brain tumor models were conducted by injections of the C6 glioma cell line (5 × 105 cell suspension) and stereotaxic techniques in the substantia nigra area. Furthermore, consumption of nanoformulation of herbals extract (100 mg/kg/day), crude extract (100 mg/kg/day), and swimming training (30 min, 3 days/week) as interventional protocols were performed for 6 weeks. In addition, we evaluated the effect of polyherbal nanoliposomes containing four plant extracts and swimming training on the GABArα1/TRKB/DRD2/DRD1a/TH network in the substantia nigra of the midbrain tumor rat model. Data emphasized that DRD2 might be a druggable protein with the network's highest significance cut-point effect that could modulate sensory-motor impairment. Furthermore, we found Quercetin, Ginsenosides, Curcumin, and Rutin, as bioactive compounds present in Ginseng, Matthiola incana, Turmeric, and Green-Tea extracts, could bind over the DRD2 protein with approved binding affinity scores. Based on our data, swimming training, and nanoliposome-enriched combined supplements could consider effective complementary medicine for motor impairment recovery induced by the midbrain tumor in the substantia nigra area. Hence, regular swimming training and natural medicines rich in polyphenolic bioactive components and antioxidative effects could modify and improve the dopamine receptors' function.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03574-3.

Flavonoids bridging the gut and the brain: intestinal metabolic fate, and direct or indirect effects of natural supporters against neuroinflammation and neurodegeneration

In recent years, experimental evidence suggested a possible role of the gut microbiota in the onset and development of several neurodegenerative disorders, such as AD and PD, MS and pain. Flavonoids, including anthocyanins, EGCG, the flavonol quercetin, and isoflavones, are plant polyphenolic secondary metabolites that have shown therapeutic potential for the treatment of various pathological conditions, including neurodegenerative diseases. This is due to their antioxidant and anti-inflammatory properties, despite their low bioavailability which often limits their use in clinical practice. In more recent years it has been demonstrated that flavonoids are metabolized by specific bacterial strains in the gut to produce their active metabolites. On the other way round, both naturally-occurring flavonoids and their metabolites promote or limit the proliferation of specific bacterial strains, thus profoundly affecting the composition of the gut microbiota which in turn modifies its ability to further metabolize flavonoids. Thus, understanding the best way of acting on this virtuous circle is of utmost importance to develop innovative approaches to many brain disorders. In this review, we summarize some of the most recent advances in preclinical and clinical research on the neuroinflammatory and neuroprotective effects of flavonoids on AD, PD, MS and pain, with a specific focus on their mechanisms of action including possible interactions with the gut microbiota, to emphasize the potential exploitation of dietary flavonoids as adjuvants in the treatment of these pathological conditions.

Regulation of mitochondrial dysfunction induced cell apoptosis is a potential therapeutic strategy for herbal medicine to treat neurodegenerative diseases

Neurodegenerative disease is a progressive neurodegeneration caused by genetic and environmental factors. Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD) are the three most common neurodegenerative diseases clinically. Unfortunately, the incidence of neurodegenerative diseases is increasing year by year. However, the current available drugs have poor efficacy and large side effects, which brings a great burden to the patients and the society. Increasing evidence suggests that occurrence and development of the neurodegenerative diseases is closely related to the mitochondrial dysfunction, which can affect mitochondrial biogenesis, mitochondrial dynamics, as well as mitochondrial mitophagy. Through the disruption of mitochondrial homeostasis, nerve cells undergo varying degrees of apoptosis. Interestingly, it has been shown in recent years that the natural agents derived from herbal medicines are beneficial for prevention/treatment of neurodegenerative diseases via regulation of mitochondrial dysfunction. Therefore, in this review, we will focus on the potential therapeutic agents from herbal medicines for treating neurodegenerative diseases via suppressing apoptosis through regulation of mitochondrial dysfunction, in order to provide a foundation for the development of more candidate drugs for neurodegenerative diseases from herbal medicine.

A review: traditional herbs and remedies impacting pathogenesis of Parkinson's disease

Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons, leading to misbalance and loss of coordination. Current therapies are claimed only for symptomatic relief, on long-term use, which causes alteration in basal ganglia, and give rise to various adverse effects like dyskinesia and extra pyramidal side effects, which is reversed and proved to be attenuated with the help of various herbal approaches. Therefore, in order to attenuate the dopaminergic complications, focus of current research has been shifted from dopaminergic to non-dopaminergic strategies. Herbs and herbal remedies seems to be a better option to overcome the complications associated with current dopaminergic therapies. In recent years, various herbs and herbal remedies based on Ayurveda, traditional Chinese and Korean remedies, have become the target of various researches. These herbs and their bioactive compound are being extensively used to treat PD in India, China, Japan, and Korea. The major focus of this current review is to analyze preclinical studies with reference to various herbs, bioactive compounds, and traditional remedies for the management of Parkinson disorder, which will give an insight towards clinical trials.

Role of Thioredoxin-1 and its inducers in human health and diseases

Thioredoxin-1 (Trx-1) is a small redox-active protein normally found in mammalian cells that responds to the changing redox environment by contributing electrons or regulating related proteins. There is growing evidence that Trx-1 has multiple functions, including cytoprotective, anti-apoptotic, antioxidant and anti-inflammatory effects. To date, researchers have found that Trx-1 deficiency leads to severe damage in various disease models, such as atherosclerosis, cerebral ischemia, diabetes and tumors. Conversely, activation of Trx-1 has a protective effect against these diseases. Accordingly, a variety of Trx-1 inducers have been widely used in the clinic with significant therapeutic value. In this paper, we summarize the pathogenesis of Trx-1 involvement in the above-mentioned diseases and describe the protective effects of Trx-1 inducers on them.

The Positive Role and Mechanism of Herbal Medicine in Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disease, manifested by the progressive functional impairment of the midbrain nigral dopaminergic neurons. Due to the unclear underlying pathogenesis, disease-modifying drugs for PD remain elusive. In Asia, such as in China and India, herbal medicines have been used in the treatment of neurodegenerative disease for thousands of years, which recently attracted considerable attention because of the development of curative drugs for PD. In this review, we first summarized the pathogenic factors of PD including protein aggregation, mitochondrial dysfunction, ion accumulation, neuroinflammation, and oxidative stress, and the related recent advances. Secondly, we summarized 32 Chinese herbal medicines (belonging to 24 genera, such as Acanthopanax, Alpinia, and Astragalus), 22 Chinese traditional herbal formulations, and 3 Indian herbal medicines, of which the ethanol/water extraction or main bioactive compounds have been extensively investigated on PD models both in vitro and in vivo. We elaborately provided pictures of the representative herbs and the structural formula of the bioactive components (such as leutheroside B and astragaloside IV) of the herbal medicines. Also, we specified the potential targets of the bioactive compounds or extractions of herbs in view of the signaling pathways such as PI3K, NF-κB, and AMPK which are implicated in oxidative and inflammatory stress in neurons. We consider that this knowledge of herbal medicines or their bioactive components can be favorable for the development of disease-modifying drugs for PD.

Duzhong Fang Attenuates the POMC-Derived Neuroinflammation in Parkinsonian Mice

BACKGROUND

Neuroinflammation and microglia reactivity are now recognized to be features of Parkinson's disease (PD). Thus, microglia phenotype is a potential new target for developing treatments against PD. Duzhong Fang (DZF) is a traditional Chinese medicine (TCM) prescription. The theory of TCM argues that Duzhong Fang, nourishing yin and tonifying yang, may treat PD. However, its modern pharmacological studies and the underlying mechanisms are unclear.

METHODS

First, MPTP was used to establish a parkinsonian mouse model, and behavioral testing was used to evaluate the locomotor dysfunction. Then, HPLC, immunohistochemical staining, and Western blot assays were performed to evaluate the survival of dopaminergic neurons. Molecular biological and immunofluorescence staining were used to evaluate the neuroinflammation and microglial activation. In addition, RNA-seq transcriptomics was used to analyze differentially expressed genes and verify by RT-PCR.

RESULTS

In the present study, we first confirmed that DZF can alleviate neuroinflammation and ameliorate dyskinesia in parkinsonian mice. Then, further studies found that DZF can regulate microglial morphology and reactivity and act on the POMC gene. POMC is an upstream target for regulating inflammation and proinflammatory cytokines, and DZF can directly inhibit the POMC level and restore the homeostatic signature of microglia in parkinsonian mice.

CONCLUSION

This study found that POMC may have a potential role as a therapeutic target for PD. DZF may inhibit neuroinflammation and play an anti-PD effect by down-regulating the expression of POMC.

Anti-neuroinflammatory effect of agaves and cantalasaponin-1 in a model of LPS-induced damage

Chronic neuroinflammation is a key component of many neurodegenerative disorders. Chronic activation of this process produces pro-inflammatory cytokines, prostaglandins and reactive oxygen species that induce brain injury and neuronal dysfunction. Agave species contain saponins, compounds with anti-inflammatory activity. Extracts from A. tequilana (At), A. angustifolia (Aan), A. Americana (Aam) (125 mg/kg) and cantalasaponin-1 (5 and 10 mg/kg, isolated from Aam) were administered to male ICR mice with lipopolysaccharide (LPS)-induced neuroinflammation, after which inflammatory cytokines were measured in brain homogenates by using an enzyme-linked immunoassay (ELISA) test. All agave extracts and cantalasaponin-1, reduced brain concentration of LPS-induced pro-inflammatory cytokines IL-6 and TNF-α. Moreover, Cantalasaponin-1 increased the brain concentration of the anti-inflammatory cytokine IL-10. Agave extracts and derived compounds show promising results in the development of novel drugs for neuroinflammatory disease therapy.

Panax notoginseng saponins and their applications in nervous system disorders: a narrative review

Panax notoginseng saponins (PNS), also called "sanqi" in Chinese, are the main active ingredients which are extracted from the root of Panax notoginseng (Burk.) F. H. Chen., and they have been traditionally used as a medicine in China for hundreds of years with magical medicinal value. PNS have varied biological functions, such as anti-inflammatory effects, anti-cancer effects, anti-neurotoxicity, and the prevention of diabetes. Nervous system disorders, a spectrum of diseases originating from the nervous system, have a significant impact on all aspects of patients' lives. Due to the dramatic gains in global life expectancy, the prevalence of nervous system disorders is growing gradually. Even if the mechanism of these diseases is still not clear, they are mainly characterized by neuronal dysfunction and neuronal death. Consequently, it is essential to find measures to slow down or prevent the onset of these diseases. At present, traditional Chinese medicines, as well as their active components, have gained widespread popularity in preventing and treating these diseases because of their merits, especially PNS. In this review, we predominantly address the recent advances in PNS researches and their biological functions, and highlight their applications in nervous system disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and stroke.

Mitochondrial connection to ginsenosides

Mitochondria play an essential role in energy synthesis and supply, thereby maintaining cellular function, survival, and energy homeostasis via mitochondria-mediated pathways, including apoptosis and mitophagy. Ginsenosides are responsible for most immunological and pharmacological activities of ginseng, a highly beneficial herb with antioxidant, anti-inflammatory, anti-apoptotic, and neuroprotective properties. Studies have shown that ginsenosides assist in regulating mitochondrial energy metabolism, oxidative stress, biosynthesis, apoptosis, mitophagy, and the status of membrane channels, establishing mitochondria as one of their most important targets. This article reviews the regulatory effects of ginsenosides on the mitochondria and highlights their beneficial role in treating mitochondrial diseases.

Anti-neuroinflammatory effects of Eucommia ulmoides Oliv. In a Parkinson's mouse model through the regulation of p38/JNK-Fosl2 gene expression

ETHNOPHARMACOLOGICAL RELEVANCE

Eucommia ulmoides Oliv., a Chinese medicinal herb called "Duzhong" from the bark of Eucommia ulmoides Oliv., has been shown to possess significant protective effects in Parkinson's disease (PD). However, the molecular mechanism remains unclear.

AIM OF THE STUDY

In this study, we explored the anti-neuroinflammatory mechanisms of Duzhong on the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model to elucidate the traditional medical theories with modern pharmacological methods and to provide a reference for further clarifying its mechanisms of action.

MATERIALS AND METHODS

The representative components in Duzhong extract were identified by UPLC-Q-TOF/MS. Male C57BL/6J mice were intraperitoneally injected with MPTP to establish an in vivo PD model. The pole, rotarod, and grip strength tests were performed to evaluate the motor coordination ability of the PD mice. HPLC-ECD was used to detect the striatal levels of dopamine (DA), 3,4- dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). The expression of tyrosine hydroxylase (TH) was studied by immunohistochemistry (IHC) and Western blot assays. ELISA and Q-PCR were used examined the levels of proinflammatory cytokines in the serum and midbrain, respectively. Whole-transcriptome analysis of the midbrain was performed to explore the therapeutic effect of Duzhong on PD mice, and Q-PCR was then used to validate the differential gene expression changes in the PD mice treated with Duzhong.

RESULTS

Ten compounds were identified from Duzhong extract. Duzhong significantly alleviated the behavioral impairments and dopaminergic neuron degeneration of PD mice, and inhibited the expression of proinflammatory cytokines. Whole-transcriptome analysis revealed nine oppositely regulated genes, and the Fosl2 gene was consistent with the trend of observed by RNA-seq. Furthermore, Duzhong downregulated mRNA expression of p38 and JNK, which are key upstream genes of Fosl2.

CONCLUSIONS

Duzhong has promising therapeutic potential in PD mice, and its molecular mechanism is mediated by downregulating p38/JNK-Fosl2 gene expression to alleviate neuroinflammation.

Notoginsenoside R1 Protects Against the Acrylamide-Induced Neurotoxicity via Upregulating Trx-1-Mediated ITGAV Expression: Involvement of Autophagy

Acrylamide (ACR) is a common chemical used in various industries and it said to have chronic neurotoxic effects. It is produced during tobacco smoking and is also generated in high-starch foods during heat processing. Notoginsenoside R1 (NR1) is a traditional Chinese medicine, which is used to improve the blood circulation and clotting. The objective of this study was to investigate the mechanism of ACR-triggered neurotoxicity and to identify the protective role of NR1 by upregulating thioredoxin-1 (Trx-1). Our results have shown that NR1 could block the spatial and cognitive impairment caused by ACR administration. Bioinformatics analysis revealed that Trx-1 regulated autophagy via Integrin alpha V (ITGAV). NR1 could resist the ACR-induced neurotoxicity by upregulating thioredoxin-1 in PC12 cells and mice. The autophagy-related proteins like autophagy-related gene (ATG) 4B, Cathepsin D, LC3 II, lysosomal-associated membrane protein 2a (LAMP2a), and ITGAV were restored to normal levels by NR1 treatment in both PC12 cells and mice. Besides, we also found that overexpression of Trx-1 resisted ACR-induced autophagy in PC12 cells and downregulation of Trx-1 triggered autophagy induced by ACR in PC12 cells. Therefore, it could be concluded that Trx-1 was involved in the autophagy pathway. Besides, we also found that ITGAV was an intermediate node linking Trx-1 and the autophagy pathway.

Panaxatriol Saponins Promote M2 Polarization of BV2 Cells to Reduce Inflammation and Apoptosis after Glucose/Oxygen Deprivation by Activating STAT3

Panaxatriol saponins (PTS) have a long history in the treatment of stroke. In our previous experiments, PTS has been found to alleviate ischemic stroke and play a role through regulating the inflammatory response, but the specific mechanism of its regulation is still unclear. Cell viability was determined by MTT assay. Expressions of polarization-related proteins CD16, CD68, ARG1 and CD206; inflammatory factors interleukin-1β (IL-1β); inducible nitric oxide synthase (iNOS); monocyte chemotactic protein 1(MCP-1) and cyclooxygenase-2 (COX-2); apoptosis-related proteins pro-caspase3; bax; caspase3 and bcl-2; and STAT3 and p-STAT3 were detected by western blot. ELISA was used to detect the expression of inflammatory-related factors in cells. The apoptosis rate was detected by flow cytometry. We found that the survival rate of oxygen sugar deprivation/reoxygenation (OGD/R) cells increased obviously after PTS treatment in a dose-dependent manner. PTS can promote M2 polarization of microglial cells (BV2) and inhibit inflammatory response of OGD/R cells, accompanied by decreased expression of inflammatory factors IL-1β, iNOS, MCP-1, and COX-2. PTS inhibited apoptosis of OGD/R cells and was accompanied by decreased expression of apoptotic proteins Bax and caspase3 and increased expression of Bcl-2. We also found that PTS activated STAT3 levels in BV2 cells. After the addition of STAT3 inhibitor Stattic, it was found that PTS could promote M2 polarization of BV2 cells by activating the STAT3 pathway, thus inhibiting cell inflammation and apoptosis. PTS promoted M2 polarization in microglia cells by activating the STAT3 pathway, thereby reducing cell inflammation and apoptosis after glucose/oxygen deprivation.

DPYSL2 is a novel regulator for neural stem cell differentiation in rats: revealed by Panax notoginseng saponin administration

BACKGROUND

The limited neuronal differentiation of the endogenous or grafted neural stem cells (NSCs) after brain injury hampers the clinic usage of NSCs. Panax notoginseng saponins (PNS) were extensively used for their clinical value, such as in controlling blood pressure, blood glucose, and inhibiting neuronal apoptosis and enhancing neuronal protection, but whether or not it exerts an effect in promoting neuronal differentiation of the endogenous NSCs is completely unclear and the potential underlying mechanism requires further exploration.

METHODS

Firstly, we determined whether PNS could successfully induce NSCs to differentiate to neurons under the serum condition. Mass spectrometry and quantitative polymerase chain reaction (Q-PCR) were then performed to screen the differentially expressed proteins (genes) between the PNS + serum and serum control group, upon which dihydropyrimidinase-like 2 (DPYSL2), a possible candidate, was then selected for the subsequent research. To further investigate the actual role of DPYSL2 in the NSC differentiation, DPYSL2-expressing lentivirus was employed to obtain DPYSL2 overexpression in NSCs. DPYSL2-knockout rats were constructed to study its effects on hippocampal neural stem cells. Immunofluorescent staining was performed to identify the differentiation direction of NSCs after 7 days from DPYSL2 transfection, as well as those from DPYSL2-knockout rats.

RESULTS

Seven differentially expressed protein spots were detected by PD Quest, and DPYSL2 was found as one of the key factors of NSC differentiation in a PNS-treated condition. The results of immunostaining further showed that mainly Tuj1 and GFAP-positive cells increased in the DPYSL2-overexpressed group, while both were depressed in the hippocampal NSCs in the DPYSL2-knockout rat.

CONCLUSIONS

The present study revealed that the differentiation direction of NSCs could be enhanced through PNS administration, and the DPYSL2 is a key regulator in promoting NSC differentiation. These results not only emphasized the effect of PNS but also indicated DPYSL2 could be a novel target to enhance the NSC differentiation in future clinical trials.

Neuroprotective effects of notoginsenoside R1 by upregulating Trx-1 on acrylamide-induced neurotoxicity in PC12

Acrylamide (ACR) is a water-soluble chemical that is commonly used in chemical and cosmetic manufacture. Many studies have been carried out to investigate the neurotoxicity mechanisms of ACR, resulting in oxidative stress and nerve damages. One of the commonly used traditional Chinese medicines is notoginsenoside R1 (NR1). However, its mitochondrial-mediated apoptotic effect caused in ACR-induced neurotoxicity has not been reported. Our results have shown that NR1 resisted the neurotoxicity induced by ACR by upregulating the levels of thioredoxin-1 (Trx-1) in Rat adrenal chromaffin cell tumor (PC12) cells. NR1 inhibited the increase in levels of Bax, caspase-9, and caspase-3, which was instigated by ACR. Moreover, NR1 inhibited the decrease in levels of B-cell lymphoma 2 and Trx-1 induced by ACR. The downregulation of Trx-1 aggravated the mitochondrial-mediated apoptosis and increased the expression of the above molecules, which was induced by ACR. In contrast, overexpression of Trx-1 attenuated the mitochondrial-mediated apoptosis and inhibited the expression of the mentioned molecules induced by ACR. Our results suggested that NR1 protected ACR-induced mitochondrial apoptosis by upregulating Trx-1.

Chinese Herbal Medicine Xueshuantong Enhances Cerebral Blood Flow and Improves Neural Functions in Alzheimer's Disease Mice

Reduced cerebral blood flow in Alzheimer's disease (AD) may occur in early AD, which contributes to the pathogenesis and/or pathological progression of AD. Reversing this deficit may have therapeutic potential. Certain traditional Chinese herbal medicines (e.g., Saponin and its major component Xueshuantong [XST]) increase blood flow in humans, but whether they could be effective in treating AD patients has not been tested. We found that systemic XST injection elevated cerebral blood flow in APP/PS1 transgenic mice using two-photon time-lapse imaging in the same microvessels before and after injection. Subchronic XST treatment led to improved spatial learning and memory and motor performance in the APP/PS1 mice, suggesting improved neural plasticity and functions. Two-photon time lapse imaging of the same plaques revealed a reduction in plaque size after XST treatment. In addition, western blots experiments showed that XST treatment led to reduced processing of amyloid-β protein precursor (AβPP) and enhanced clearance of amyloid-β (Aβ) without altering the total level of AβPP. We also found increased synapse density in the immediate vicinity of amyloid plaques, suggesting enhanced synaptic function. We conclude that targeting cerebral blood flow can be an effective strategy in treating AD.

Plant Extracts and Phytochemicals Targeting α-Synuclein Aggregation in Parkinson's Disease Models

α-Synuclein (α-syn) is a presynaptic protein that regulates the release of neurotransmitters from synaptic vesicles in the brain. α-Syn aggregates, including Lewy bodies, are features of both sporadic and familial forms of Parkinson's disease (PD). These aggregates undergo several key stages of fibrillation, oligomerization, and aggregation. Therapeutic benefits of drugs decline with disease progression and offer only symptomatic treatment. Novel therapeutic strategies are required which can either prevent or delay the progression of the disease. The link between α-syn and the etiopathogenesis and progression of PD are well-established in the literature. Studies indicate that α-syn is an important therapeutic target and inhibition of α-syn aggregation, oligomerization, and fibrillation are an important disease modification strategy. However, recent studies have shown that plant extracts and phytochemicals have neuroprotective effects on α-syn oligomerization and fibrillation by targeting different key stages of its formation. Although many reviews on the antioxidant-mediated, neuroprotective effect of plant extracts and phytochemicals on PD symptoms have been well-highlighted, the antioxidant mechanisms show limited success for translation to clinical studies. The identification of specific plant extracts and phytochemicals that target α-syn aggregation will provide selective molecules to develop new drugs for PD. The present review provides an overview of plant extracts and phytochemicals that target α-syn in PD and summarizes the observed effects and the underlying mechanisms. Furthermore, we provide a synopsis of current experimental models and techniques used to evaluate plant extracts and phytochemicals. Plant extracts and phytochemicals were found to inhibit the aggregation or fibril formation of oligomers. These also appear to direct α-syn oligomer formation into its unstructured form or promote non-toxic pathways and suggested to be valuable drug candidates for PD and related synucleinopathy. Current evidences from in vitro studies require confirmation in the in vivo studies. Further studies are needed to ascertain their potential effects and safety in preclinical studies for pharmaceutical/nutritional development of these phytochemicals or dietary inclusion of the plant extracts in PD treatment.

Neuroprotective effects of genistein on SH-SY5Y cells overexpressing A53T mutant α-synuclein

Genistein, a potent antioxidant compound, protects dopaminergic neurons in a mouse model of Parkinson's disease. However, the mechanism underlying this action remains unknown. This study investigated human SH-SY5Y cells overexpressing the A53T mutant of α-synuclein. Four groups of cells were assayed: a control group (without any treatment), a genistein group (incubated with 20 μM genistein), a rotenone group (treated with 50 μM rotenone), and a rotenone + genistein group (incubated with 20 μM genistein and then treated with 50 μM rotenone). A lactate dehydrogenase release test confirmed the protective effect of genistein, and genistein remarkably reversed mitochondrial oxidative injury caused by rotenone. Western blot assays showed that BCL-2 and Beclin 1 levels were markedly higher in the genistein group than in the rotenone group. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling revealed that genistein inhibited rotenone-induced apoptosis in SH-SY5Y cells. Compared with the control group, the expression of NFE2L2 and HMOX1 was significantly increased in the genistein + rotenone group. However, after treatment with estrogen receptor and NFE2L2 channel blockers (ICI-182780 and ML385, respectively), genistein could not elevate NFE2L2 and HMOX1 expression. ICI-182780 effectively prevented genistein-mediated phosphorylation of NFE2L2 and remarkably suppressed phosphorylation of AKT, a protein downstream of the estrogen receptor. These findings confirm that genistein has neuroprotective effects in a cell model of Parkinson's disease. Genistein can reduce oxidative stress damage and cell apoptosis by activating estrogen receptors and NFE2L2 channels.

Revealing the Inhibitory Effect of Ginseng on Mitochondrial Respiration through Synaptosomal Proteomics

Ginseng, the active ingredients of which are ginsenosides, is the most popular herbal medicine and has potential merit in the treatment of cerebral disorders. To better understand the function of Ginseng in the cerebral system, we examined changes in the protein expression profiles of synaptosomes extracted from the cerebral cortical and hippocampal tissues of rats administered a high or low dose of Ginseng for 2 weeks. More than 5000 proteins belonging to synaptosomes were simultaneously identified and quantitated by an approach combining tandem mass tags with 2D liquid chromatography-mass spectrometry (LC-MS). Regarding differentially expressed proteins, downregulated proteins were much more highly induced than upregulators in the cerebral cortical and hippocampal synaptosomes, regardless of the dose of Ginseng. Bioinformatic analysis indicated the majority of the altered proteins to be located in the mitochondria, directly or indirectly affecting mitochondrial oxidative respiration. Further functional experiments using the substrate-uncoupler inhibitor titration approach confirmed that three representative ginsenosides were able to inhibit oxidative phosphorylation in mitochondria. Our results demonstrate that Ginseng can regulate the function of mitochondria and alter the energy metabolism of cells, which may be useful for the treatment of central nervous disorders.

Panax notoginseng for Inflammation-Related Chronic Diseases: A Review on the Modulations of Multiple Pathways

Panax notoginseng (P. notoginseng) is a well-known and commonly used Chinese herbal medicine in Asian countries. As one of the major species in the Panax genus, it has a distinct chemical composition and medical application compared with other species. P. notoginseng attracts attention and interest due to its potential therapeutic effects not only on blood diseases, but also other kinds of human chronic disorders. This paper critically reviewed the latest advance of knowledge on the pharmacological effects of P. notoginseng on a variety of chronic diseases including inflammatory bowel disease, arthritis, ischemia, atherosclerosis, Alzheimer disease and trauma, as well as hyperlipidemia, diabetes, and so on. As inflammation is considered the fundamental factor involved in the pathogenesis of chronic diseases, our review therefore focuses on understanding the involvement of classical inflammatory pathways underlying the mechanism of action of P. notoginseng. Potential clinical application was also discussed. Furthermore, by combining with network pharmacology, we introduced the major bioactive components of P. notoginseng, analyzed their cellular targets and associated signaling pathways. In conclusion, this review identified inflammatory pathway as the key signaling for determining the efficacy of P. notoginseng on chronic diseases. It is speculated that P. notoginseng is a multi-targeted agent with an anti-inflammatory property in the adjuvant and alternative treatment of human chronic diseases.

Therapeutic Potential and Cellular Mechanisms of Panax Notoginseng on Prevention of Aging and Cell Senescence-Associated Diseases

Owing to a dramatic increase in average life expectancy, most countries in the world are rapidly entering an aging society. Therefore, extending health span with pharmacological agents targeting aging-related pathological changes, are now in the spotlight of gerosciences. Panax notoginseng (Burk.) F. H. Chen, a species of the genus Panax, has been called the "Miracle Root for the Preservation of Life," and has long been used as a Chinese herb with magical medicinal value. Panax notoginseng has been extensively employed in China to treat microcirculatory disturbances, inflammation, trauma, internal and external bleeding due to injury, and as a tonic. In recent years, with the deepening of the research pharmacologically, many new functions have been discovered. This review will introduce its pharmacological function on lifespan extension, anti-vascular aging, anti-brain aging, and anti-cancer properties, aiming to lay the ground for fully elucidating the potential mechanisms of Panax notoginseng's anti-aging effect to promote its clinical application.

Plants-Derived Neuroprotective Agents: Cutting the Cycle of Cell Death through Multiple Mechanisms

Neuroprotection is the preservation of the structure and function of neurons from insults arising from cellular injuries induced by a variety of agents or neurodegenerative diseases (NDs). The various NDs including Alzheimer's, Parkinson's, and Huntington's diseases as well as amyotropic lateral sclerosis affect millions of people around the world with the main risk factor being advancing age. Each of these diseases affects specific neurons and/or regions in the brain and involves characteristic pathological and molecular features. Hence, several in vitro and in vivo study models specific to each disease have been employed to study NDs with the aim of understanding their underlying mechanisms and identifying new therapeutic strategies. Of the most prevalent drug development efforts employed in the past few decades, mechanisms implicated in the accumulation of protein-based deposits, oxidative stress, neuroinflammation, and certain neurotransmitter deficits such as acetylcholine and dopamine have been scrutinized in great detail. In this review, we presented classical examples of plant-derived neuroprotective agents by highlighting their structural class and specific mechanisms of action. Many of these natural products that have shown therapeutic efficacies appear to be working through the above-mentioned key multiple mechanisms of action.

Effect and Mechanism of Chinese Herbal Medicine on Parkinson's Disease

Parkinson's disease is a progressive neurodegenerative disorder. Although both genetic and environmental factors are implicated in the development of Parkinson's disease, the cause of the disease is still unclear. So far conventional treatments to Parkinson's are symptomatic relief and focused mainly on motor symptoms. Chinese herbal medicine has been used to treat many conditions in China, Korea, Japan, and many Southeast Asian countries for 1000 years. During past a few decades, Chinese herbal medicine has gained wider and increasing acceptance within both public and medical profession due to its effectiveness on many conditions in western countries. In this chapter, mechanisms of action of many Chinese herbal compounds/extracts and Chinese herb formulas on the models of Parkinson's were reviewed. Further, reports of effectiveness of Chinese herb formulas on patients with Parkinson's were summarized. It was shown that both Chinese herbal compounds/extracts and herb formulas have either specific target mechanisms of action or multitargets mechanisms of action, as antioxidant, antiinflammatory, and antiapoptosis agents. Clinical studies showed that Chinese herb formulas as an adjunct improved both motor and nonmotor symptoms, and reduced dose of dopaminergic drugs and occurrence of dyskinesia. The evidence from the studies suggests that Chinese herb medicine has potential, acting as neuroprotective to slow down the progression of Parkinson's, and it is able to simultaneously treat both motor and nonmotor symptoms of Parkinson's. More studies are needed to explore the new compounds/extracts derived from Chinese herbs, in particular, their mechanisms of action. It is hopeful that new drugs developed from Chinese herb compounds/extracts and Chinese herb formulas will lead to better and complimentary therapy to PD.

Panaxatriol saponins promotes angiogenesis and enhances cerebral perfusion after ischemic stroke in rats

Background

Panaxatriol saponins (PTS), an extract from the traditional Chinese herb Panax notoginseng, which has been used to treat ischemic stroke for many years in China. However, the mechanism underlying the effects of PTS remains unclear. This study aimed to determine whether PTS can protect against ischemic brain injury by promoting angiogenesis and to explore the possible mechanism by which it promotes angiogenesis.

Methods

Middle cerebral artery occlusion (MCAO) was induced in rats, and neurological deficit scores and brain infarct volumes were assessed. Micro-Positron emission tomography (PET) was adopted to assess cerebral perfusion, and real-time PCR and western blotting were used to evaluate vascular growth factor and Sonic hedgehog (Shh) pathway component levels. Immunofluorescence staining was used to determine capillary densities in ischemic penumbrae.

Results

We showed that PTS improved neurological function and reduced infarct volumes in MCAO rats. Micro-PET indicated that PTS can significantly increase ¹⁸F-fluorodeoxyglucose (¹⁸F-PDG) uptake by ischemic brain tissue and enhance cerebral perfusion after MCAO surgery. Moreover, PTS was able to increase capillary densities and enhance angiogenesis in ischemic boundary zones and up-regulate vascular endothelial growth factor (VEGF) and Angiopoietin-1 (Ang-1) expression by activating the Shh signaling pathway.

Conclusion

These findings indicate that PTS exerts protective effects against cerebral ischemic injury by enhancing angiogenesis and improving microperfusion.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1579-5) contains supplementary material, which is available to authorized users.

A Role of Ginseng and Its Constituents in the Treatment of Central Nervous System Disorders

Ginseng, a perennial plant belonging to the Panax genus of the Araliaceae family, has been used in China, Korea, and Japan as a traditional herbal medicine for thousands of years. Ginseng is recorded to have exhibited a wide variety of beneficial pharmacological effects and has become a popular and worldwide known health supplement and drug. The protective effects of ginseng on central nervous system are discussed in this review. Ginseng species and ginsenosides and their intestinal metabolism and bioavailability are concisely introduced. The molecular mechanisms of the effects of ginseng on central nervous system, mainly focused on the neuroprotection properties of ginseng, memory, and learning enhanced properties, and the effects on neurodegenerative disorders are presented. Thus, ginseng and its constituents are of potential merits in the treatment of cerebral disorders.

Therapeutic Potential of Natural Product-Based Oral Nanomedicines for Stroke Prevention

Cerebral stroke is the leading cause of death and permanent disability in elderly persons. The impaired glucose and oxygen transport to the brain during ischemia causes bioenergetic failure, leading to oxidative stress, inflammation, blood-brain barrier dysfunction, and eventually cell death. However, the development of effective therapies against stroke has been hampered by insufficient oral absorption of pharmaceuticals and subsequent delivery to the brain. Nanotechnology has emerged as a new method of treating cerebral diseases, with the potential to fundamentally change currently available therapeutic approaches using compounds with low bioavailability. This perspective review provides an overview of the therapeutic potential of oral nanomedicines for stroke, focusing on novel natural product-loaded delivery system with potent antioxidant and anti-inflammatory effects.

Plant-Derived Natural Products for Parkinson's Disease Therapy

Plant-derived natural products have made their own niche in the treatment of neurological diseases since time immemorial. Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, has no cure and the treatment available currently is symptomatic. This chapter thoughtfully and objectively assesses the scientific basis that supports the increasing use of these plant-derived natural products for the treatment of this chronic and progressive disorder. Proper considerations are made on the chemical nature, sources, preclinical tests and their validity, and mechanisms of behavioural or biochemical recovery observed following treatment with various plants derived natural products relevant to PD therapy. The scientific basis underlying the neuroprotective effect of 6 Ayurvedic herbs/formulations, 12 Chinese medicinal herbs/formulations, 33 other plants, and 5 plant-derived molecules have been judiciously examined emphasizing behavioral, cellular, or biochemical aspects of neuroprotection observed in the cellular or animal models of the disease. The molecular mechanisms triggered by these natural products to promote cell survivability and to reduce the risk of cellular degeneration have also been brought to light in this study. The study helped to reveal certain limitations in the scenario: lack of preclinical studies in all cases barring two; heavy dependence on in vitro test systems; singular animal or cellular model to establish any therapeutic potential of drugs. This strongly warrants further studies so as to reproduce and confirm these reported effects. However, the current literature offers scientific credence to traditionally used plant-derived natural products for the treatment of PD.

Protective effects of ginseng on neurological disorders

Ginseng (Order: Apiales, Family: Araliaceae, Genus: Panax) has been used as a traditional herbal medicine for over 2000 years, and is recorded to have antianxiety, antidepressant and cognition enhancing properties. The protective effects of ginseng on neurological disorders are discussed in this review. Ginseng species and ginsenosides, and their intestinal metabolism and bioavailability are briefly introduced. This is followed by molecular mechanisms of effects of ginseng on the brain, including glutamatergic transmission, monoamine transmission, estrogen signaling, nitric oxide (NO) production, the Keap1/Nrf2 adaptive cellular stress pathway, neuronal survival, apoptosis, neural stem cells and neuroregeneration, microglia, astrocytes, oligodendrocytes and cerebral microvessels. The molecular mechanisms of the neuroprotective effects of ginseng in Alzheimer’s disease (AD) including β-amyloid (Aβ) formation, tau hyperphosphorylation and oxidative stress, major depression, stroke, Parkinson’s disease and multiple sclerosis are presented. It is hoped that this discussion will stimulate more studies on the use of ginseng in neurological disorders.

Neuroprotection by saponins

Saponins, an important group of bioactive plant natural products, are glycosides of triterpenoid or steroidal aglycones. Their diverse biological activities are ascribed to their different structures. Saponins have long been recognized as key ingredients in traditional Chinese medicine. Accumulated evidence suggests that saponins have significant neuroprotective effects on attenuation of central nervous system disorders, such as stroke, Alzheimer's disease, Parkinson's disease, and Huntington's disease. However, our understanding of the mechanisms underlying the observed effects remains incomplete. Based on recently reported data from basic and clinical studies, this review highlights the proposed mechanisms of their neuroprotective function including antioxidant, modulation of neurotransmitters, anti-apoptosis, anti-inflammation, attenuating Ca(2+) influx, modulating neurotrophic factors, inhibiting tau phosphorylation, and regeneration of neural networks.

Xueshuantong improves cerebral blood perfusion in elderly patients with lacunar infarction

A total of 64 patients with acute lacunar infarction were enrolled within 24 hours of onset. The patients received conventional therapy (antiplatelet drugs and hypolipidemic drugs) alone or conventional therapy plus 450 mg Xueshuantong once a day. The main ingredient of the Xueshuantong lyophilized powder used for injection was Panax notoginseng saponins. Assessments were made at admission and at discharge using the National Institutes of Health Stroke Scale, the Activity of Daily Living and the Mini-Mental State Examination. Additionally, the relative cerebral blood flow, relative cerebral blood volume and relative mean transit time in the region of interest were calculated within 24 hours after the onset of lacunar infarction, using dynamic susceptibility contrast magnetic resonance perfusion imaging technology. Patients underwent a follow-up MRI scan after 4 weeks of treatment. There was an improvement in the Activity of Daily Living scores and a greater reduction in the scores on the National Institutes of Health Stroke Scale in the treatment group than in the control group. However, the Mini-Mental State Examination scores showed no significant differences after 4 weeks of treatment. Compared with the control group, the relative cerebral blood flow at discharge had increased and showed a greater improvement in the treatment group. Furthermore, there was a reduction in the relative mean transit time at discharge and the value was lower in the treatment group than in the control group. The experimental findings indicate that Xueshuantong treatment improves neurological deficits in elderly patients with lacunar infarction, and the mechanism may be related to increased cerebral perfusion.

Rapid but mild genoprotective effect on lymphocytic DNA with Panax notoginseng extract supplementation

BACKGROUND

Panax notoginseng (PN) is a well-known Chinese medicinal herb traditionally used as a hemostatic agent that strengthens and builds blood. The free radicals scavenging and antioxidant property of PN have been demonstrated in various studies either in vitro or in animal models, however, the genoprotective effect at human cellular level remains to be elucidated.

AIM

The current supplementation study aimed to investigate the genoprotective effect of PN. The study explored the DNA protection effect after a single dose of 2500 mg commercial notoginseng extract in water.

MATERIALS AND METHODS

Six subjects, (3 males, 3 females) were recruited and each attended two trials. In the first trial, pre-ingestion and 2 hour-post-ingestion blood samples were collected and they were challenged with 50 µM H2O2. In the second trial, water was taken instead as control. Lymphocytes with or without challenge were then subjected to comet assay. DNA damage was assessed under fluorescent microscope.

RESULTS

Results showed a significant (P < 0.05) but mild decrease (3%) in the comet score after PN supplementation, indicating that PN supplementation reduces the H2O2-induced DNA damage in the lymphocytes and enhanced their resistance to oxidative damage giving a mild acute genoprotective effect against oxidant challenge. No change of comet score was observed in control trial.

Panaxatriol saponin ameliorated liver injury by acetaminophen via restoring thioredoxin-1 and pro-caspase-12

BACKGROUND & AIMS

Acetaminophen (APAP) is widely used as an antipyretic agent which is safe at therapeutic doses. However, overdose of APAP induces fatal and non-fatal hepatic necroses. The chemical reactive metabolites of APAP initiate toxicity and inflammatory response within the liver and lead to acute liver failure. However, the mechanism underlying APAP-induced liver injury is unknown. Thioredoxin-1 (TRX-1) is an important redox regulator, which plays roles in resisting oxidative stress, regulating inflammation and inhibiting apoptosis. Panaxatriol saponin (PTS) is one of the biologically active fractions of Panax notoginseng which is a traditional Chinese medicine. The aim of this study was to investigate the mechanism on PTS protecting liver from APAP hepatotoxicity.

METHODS

Mice were divided into three groups, control group, APAP group and APAP combined with PTS group. Alanine aminotransferase (ALT) and tumour necrosis factor-alpha (TNF-α) were detected by ELISA. TRX-1 and pro-caspase-12 were examined by Western blotting.

RESULTS

Our results showed PTS inhibited the levels of ALT and TNF-α by APAP. Pretreatment with PTS ameliorated liver injury induced by APAP. The decrease in TRX-1 expression was restored by PTS, as well as decreased pro-caspase-12 expression was inhibited by PTS. These data suggest that PTS has roles in suppressing the hepatotoxicity by APAP.

CONCLUSION

Panaxatriol saponin ameliorated liver injury by APAP through restoring the expression TRX-1 and inhibiting pro-caspase-12 decrease.

The role of thioredoxin-1 in suppression of endoplasmic reticulum stress in Parkinson disease

Endoplasmic reticulum (ER) stress has been implicated in Parkinson disease. We previously reported that thioredoxin 1 (Trx-1) suppressed the ER stress caused by 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine; however, its molecular mechanism remains largely unknown. In the present study, we showed that 1-methyl-4-phenylpyridinium ion (MPP(+)) induced ER stress by activating glucose-regulated protein 78 (GRP78), inositol-requiring enzyme 1α (IRE1α), tumor necrosis factor receptor-associated factor 2 (TRAF2), c-Jun N-terminal kinase (JNK), caspase-12, and C/EBP homologous protein (CHOP) in PC12 cells. The downregulation of Trx-1 aggravated the ER stress and further increased the expression of the above molecules induced by MPP(+). In contrast, overexpression of Trx-1 attenuated the ER stress and repressed the expression of the above molecules induced by MPP(+). More importantly, the overexpression of Trx-1 in transgenic mice suppressed ER stress by inhibiting the activation of these molecules. We present, for the first time, the molecular mechanism of Trx-1 suppression of endoplasmic reticulum stress in Parkinson disease in vitro and in vivo. Based on our findings, we conclude that Trx-1 plays a neuroprotective role in Parkinson disease by suppressing ER stress by regulating the activation of GRP78, IRE1α, TRAF2, JNK, caspase-12, and CHOP.

Panax ginseng is neuroprotective in a novel progressive model of Parkinson's disease

Panax ginseng has been used in traditional Chinese medicine for centuries. Among its various benefits is a pluripotent targeting of the various events involved in neuronal cell death. This includes anti-inflammatory, anti-oxidant, and anti-apoptotic effects. Indeed, ginseng extract and its individual ginsenosides have been demonstrated to influence a number of biochemical markers implicated in Parkinson's disease (PD) pathogenesis. We have reported previously that administration of the ginseng extract, G115, afforded robust neuroprotection in two rodent models of PD. However, these traditional rodent models are acute in nature and do accurately recapitulate the progressive nature of the disease. Chronic exposure to the dietary phytosterol glucoside, β-sitosterol β-d-glucoside (BSSG) triggers the progressive development of neurological deficits, with behavioral and cellular features that closely approximate those observed in PD patients. Clinical signs and histopathology continue to develop for several months following cessation of exposure to the neurotoxic insult. Here, we utilized this model to further characterize the neuroprotective effects of the ginseng extract, G115. Oral administration of this extract significantly reduced dopaminergic cell loss, microgliosis, and accumulation of α-synuclein aggregates. Further, G115 administration fully prevented the development of locomotor deficits, in the form of reduced locomotor activity and coordination. These results suggest that ginseng extract may be a potential neuroprotective therapy for the treatment of PD.

Therapeutic effects of traditional herbal medicine on cerebral ischemia: a perspective of vascular protection

Although many agents for acute ischemic stroke treatment have been developed from extensive preclinical studies, most have failed in clinical trials. As a result, researchers are seeking other methods or agents based on previous studies. Among the various prospective approaches, vascular protection might be the key for development of therapeutic agents for stroke and for improvements in the efficacy and safety of conventional therapies. Traditional medicines in Asian countries are based on clinical experiences and literature accumulated over thousands of years. To date, many studies have used traditional herbal medicines to prove or develop new agents based on stroke treatments mentioned in traditional medicinal theory or other clinical data. In the current review, we describe the vascular factors related to ischemic brain damage and the herbal medicines that impact these factors, including Salviae Miltiorrhizae Radix, Notoginseng Radix, and Curcumae Rhizoma, based on scientific reports and traditional medical theory. Further, we point out the problems associated with herbal medicines in stroke research and propose better methodologies to address these problems.

P90RSK and Nrf2 Activation via MEK1/2-ERK1/2 Pathways Mediated by Notoginsenoside R2 to Prevent 6-Hydroxydopamine-Induced Apoptotic Death in SH-SY5Y Cells

6-Hydroxydopamine (6-OHDA) is known to contribute to neuronal death in Parkinson's disease. In this study, we found that the preincubation of SH-SY5Y cells for 24 h with 20  μ M notoginsenoside R2 (NGR2), which is a newly isolated notoginsenoside from Panax notoginseng, showed neuroprotective effects against 6-OHDA-induced oxidative stress and apoptosis. NGR2 incubation successively resulted in the activation of P90RSK, inactivation of BAD, and inhibition of 6-OHDA-induced mitochondrial membrane depolarization, thus preventing the mitochondrial apoptosis pathway. NGR2 incubation also led to the activation of Nrf2 and subsequent activity enhancement of phase II detoxifying enzymes, thus suppressing 6-OHDA-induced oxidative stress, and these effects could be removed by Nrf2 siRNA. We also found that the upstream activators of P90RSK and Nrf2 were the MEK1/2-ERK1/2 pathways but not the JNK, P38, or PI3K/Akt pathways. Interestingly, NGR2 incubation could also activate MEK1/2 and ERK1/2. Most importantly, NGR2-mediated P90RSK and Nrf2 activation, respective downstream target activation, and neuroprotection were reversed by the genetic silencing of MEK1/2 and ERK1/2 by using siRNA and PD98059 application. These results suggested that the neuroprotection elicited by NGR2 against 6-OHDA-induced neurotoxicity was associated with NGR2-mediated P90RSK and Nrf2 activation through MEK1/2-ERK1/2 pathways.

Advances in neuroprotective ingredients of medicinal herbs by using cellular and animal models of Parkinson's disease

Parkinson's disease (PD) is a multifactorial disorder, which is neuropathologically identified by age-dependent neurodegeneration of dopaminergic neurons in the substantia nigra. Development of symptomatic treatments has been partly successful for PD research, but there remain a number of inadequacies in therapeutic strategies for the disease. The pathogenesis of PD remains intricate, and the present anti-PD treatments appears to be clinically insufficient. Comprehensive research on discovery of novel drug candidates has demonstrated that natural products, such as medicinal herbs, plant extracts, and their secondary metabolites, have great potential as therapeutics with neuroprotective activity in PD. Recent preclinical studies suggest that a number of herbal medicines and their bioactive ingredients can be developed into optimum pharmaceuticals for treating PD. In many countries, traditional herbal medicines are used to prevent or treat neurodegenerative disorders, and some have been developed as nutraceuticals or functional foods. Here we focus on recent advances of the evidence-linked neuroprotective activity of bioactive ingredients of herbal origin in cellular and animal models of PD research.

A comprehensive review of the therapeutic and pharmacological effects of ginseng and ginsenosides in central nervous system

Ginseng is one of the most widely used herbal medicines in human. Central nervous system (CNS) diseases are most widely investigated diseases among all others in respect to the ginseng’s therapeutic effects. These include Alzheimer’s disease, Parkinson’s disease, cerebral ischemia, depression, and many other neurological disorders including neurodevelopmental disorders. Not only the various types of diseases but also the diverse array of target pathways or molecules ginseng exerts its effect on. These range, for example, from neuroprotection to the regulation of synaptic plasticity and from regulation of neuroinflammatory processes to the regulation of neurotransmitter release, too many to mention. In general, ginseng and even a single compound of ginsenoside produce its effects on multiple sites of action, which make it an ideal candidate to develop multi-target drugs. This is most important in CNS diseases where multiple of etiological and pathological targets working together to regulate the final pathophysiology of diseases. In this review, we tried to provide comprehensive information on the pharmacological and therapeutic effects of ginseng and ginsenosides on neurodegenerative and other neurological diseases. Side by side comparison of the therapeutic effects in various neurological disorders may widen our understanding of the therapeutic potential of ginseng in CNS diseases and the possibility to develop not only symptomatic drugs but also disease modifying reagents based on ginseng.

Recent updates in redox regulation and free radical scavenging effects by herbal products in experimental models of Parkinson's disease

Parkinson’s disease (PD) is a complex multifactorial disease marked by extensive neuropathology in the brain with selective yet prominent and progressive loss of mid-brain dopaminergic neurons. The etiological factors involved in the development of PD are still elusive, but oxidative stress arising when reactive oxygen species (ROS) exceed amounts required for normal redox signaling is considered one of the major factors. ROS cause oxidative damage to proteins, lipids, and DNA and are one of the most prominent factors related to neurodegeneration. Pre-clinical and clinical studies clearly demonstrate the effectiveness of oxidative stress in the pathogenesis of PD. Therefore, regulation of redox signaling and inhibiting excess ROS would contribute greatly not only to extend longevity but also to ameliorate the progression of dopaminergic cell death seen in patients with PD. Several herbal products are beneficial for maintaining nerve cell function and for treating various neurodegenerative disorders by reducing oxidative stress. Here, we summarize the recent knowledge concerning promising herbs that have shown significant beneficial effects based on regulation of redox status and ROS inhibition in toxin-induced PD models.